Improvement of fermentation and the in vitro digestibility characteristics of agricultural waste-based complete feed silage with cellulase enzyme treatment

Abstract

The use of crop residues and agricultural wastes in animal feed is a very common practice to ensure a feed supply in livestock production. However, the agricultural wastes generally have high crude fiber content. The study aimed at establishing the effects of increasing cellulase levels on fermentation quality, chemical composition, and in vitro nutrient digestibility of complete feed silage containing oil palm frond and rice crop residue. The mixture of ingredients (king grass, rice crop residue, oil palm fronds, cassava waste, tofu waste, and lactic acid bacteria) were treated with (A) cellulase 0 mL/kg as control, (B) cellulase 1 mL/kg, (C) cellulase 2 mL/kg, (D) cellulase 3 mL/kg, and (E) cellulase 4 mL/kg. The initial lactic acid bacteria (LAB) concentration in inoculant was 6.6 x 105 cfu/g of fresh matter, and the cellulase enzyme used in the study was a commercial product (Novozymes). Plastic silos containing approximately 500 g of silage material for each were stored at room temperature (28-30°C) for 30 days. The results of the study showed that adding cellulase increased crude protein content (L: P < 0.01), but decreased neutral detergent fiber (NDF) (L, Q: P < 0.01), acid detergent fiber, hemicellulose (L: P < 0.01), and cellulose (L: P < 0.05) contents. The silages with cellulase treatment had high concentrations of lactic acid, but low pHs and total volatile fatty acid VFA contents, which indicated that they had been successfully preserved. Adding cellulase improved (L: P < 0.01) in vitro digestibility of dry matter, organic matter, and NDF. The study showed that adding cellulase improved fermentation quality and in vitro nutrient digestibility of agricultural and food industry-wastes based complete feed silage.